问题 选择题

下列对溶液pH的有关判断中,正确的是(  )

A.随着温度的升高,Na2CO3溶液pH减小

B.随着温度的升高,纯水的pH增大

C.向0.1mol•L-1的CH3COOH溶液中加入少量CH3COONa晶体,溶液的pH增大

D.pH=2的醋酸溶液与pH=2的H2SO4溶液的物质的量浓度之比为2:1

答案

A、碳酸钠中碳酸根的水解反应方程式:CO32-+H2O⇌HCO3-+OH-,水解过程是吸热的,温度越高弱酸根离子的水解程度越大,随着温度的升高,水解平衡向右移动,氢氧根浓度增大,碱性增强,pH增大,故A错误;

B、温度越高越有利于水的电离,水的离子积常数越大,氢离子浓度越大,pH减小,故B错误;

C、CH3COOH溶液中加入少量CH3COONa晶体,CH3COO-对醋酸的电离起抑制作用,所以酸性减弱,溶液的pH增大,故C正确;

D、醋酸是弱电解质,不完全电离,pH=2的醋酸溶液其浓度大于0.01mol/L,H2SO4是强酸,能完全电离,pH=2的H2SO4溶液的物质的量浓度为0.005mol/L,比值大于2:1,故D错误.

故选C.

完形填空

完形填空(共10小题;每小题1分,满分10分)

阅读下面短文,掌握其大意,然后从第31至第40小题所给的A、B、C、D四个选项中,选出最佳选项,并在答题卡上将该项涂黑。

With the development of industry, factories produce large amounts of   31  chemicals. These chemicals go into the atmosphere and flow into the water, making many plants and animals   32    and large areas of the world damaged.     33  , the world’s population    34  to 6.5 billion.

Some people suggest cutting back on production, thinking more about recycling and teaching people about    35   friendly ways of living.

While some people say that a healthy environment and a stable economy should be possible at the same time. They don’t think the economy development is bad for the environment, saying there are many factories and industries   36  control the amount of pollution they produce and spend money    37  any damage they cause. They are concerned   38  the environment.

The way to   39   the environment may be recycling, and making more effective laws to control the numbers of trees   40  and fishes caught. Factories should have to pay higher taxes. And many people are willing to pay higher prices for environmentally friendly things.

31.  A.  useless    B.  good       C.  poisonous                 D.  harmless

32.  A.  die  B.  dies  C.  dying                       D.  died

33.  A.  In addition     B.  In all       C.  In time                  D.  In the end

34.  A.  is grown          B.  is growing         C.  had grown                    D.  grow

35.  A.  elementary     B.  environmental C.  environmentalist     D.  environmentally

36.  A.  where      B.  which             C.  what                      D.  who

37.  A.  repaire   B.  repaired   C.  repairing                D.  to repaire

38.  A.  with       B.  about       C.  in                          D.  to

39.  A.  damage  B.  build       C.  preserve           D.  ruin

40.  A.  cut down       B.  cut off     C.  cut up             D.  cut in

问答题 简答题